This invention relates to a device for indicating the position of one part of an assembly relative to another part. One application of that kind of device is in relation to adjustment of the mantle of a gyratory crusher, and it will be convenient to hereinafter describe the invention in relation to that particular example.
The gyratory crusher mantle is usually supported in a selected position relative to the concave of the crusher, and that position is adjusted from time to time to achieve a desired "closed side setting," which is the term used to identify the minimum clearance space between the concave and the mantle. That clearance will be selected to suit end user requirements--i.e., the degree of fineness of the crushed product--and occasional adjustment may be necessary to compensate for wear. Because of the nature of the crusher construction, it is not a simple matter to accurately set and maintain the mantle position, and position indicator systems utilized to date have not been satisfactory.
In one prior indicator system, the mantle position has been determined by reference to the level of oil in the feed reservoir for the hydraulic cylinder which supports the mantle in its position relative to the inner cone. The accuracy of that system is adversely affected by small amounts of air in the oil, the inevitable loss of oil under pressure, and varying temperatures of the oil. Another proposal involves the use of an electrical displacement transducer connected to the lower end of the mantle support cylinder, but that has the disadvantage that it is not readily adaptable to existing equipment and is therefore used mainly as an original component on new equipment. The difficulty of attaching the transducer to existing equipment arises, at least in part, from the fact that the transducer assembly must be substituted for the lower end of the mantle support cylinder and projects substantially below that end of the cylinder. There is not always sufficient space to accept that projection of the assembly.